Fast analysis of derivatives of polycyclic aromatic hydrocarbons in soil by ultra-high performance supercritical fluid chromatography after supercritical fluid extraction enrichment

Abstract

An efficient and environment-friendly method for simultaneous determination of 13 typical derivatives of polycyclic aromatic hydrocarbon (PAH) in petroleum-polluted soil with nitro-, oxy- and alkyl-functional group was developed using supercritical fluid extraction (SFE) followed by ultra-high performance supercritical fluid chromatography (UHPSFC). Parameters of UHPSFC, including type of stationary phase and mobile phase modifiers, gradient elution process, backpressure, column temperature, and the flow rate of mobile phase, were systematically optimized, achieving a fast separation within 4.2 min. Limits of detection (LOD) were 0.005–0.1 μg mL−1 or 0.1–2.0 ng g−1, respectively, with a good repeatability (RSD<5.0%). Before UHPSFC-PDA analysis, the PAH-derivatives in soil samples were effectively enriched in 15.0 min using SFE with an online carbon nanotubes (CNTs) collection trap. The soil samples were analyzed by the proposed method and the results were verified by GC-MS. Thus, SFE equipped with an online CNTs trap followed by UHPSFC-PDA analysis, which only consumed about 2.0 mL organic solvent for a whole run, has been demonstrated to be an efficient way for screening and quantitative analysis of trace-level PAH-derivatives in soil samples.